Patent GB-341898-A (GB)
Title: Improvements in and relating to azo dystuffs and methods of preparing the same
IPC: C09B43/124
Filed: 1929-07-18
Abstract: Azo dyes; azo dyes, forming on the material.-Secondary disazo and trisazo dyes are obtained by diazotizing a sulphonated aromatic amine or aminoazo compound free from nuclear hydroxyl groups, coupling with an amine free from hydroxyl groups, condensing the aminoazo or aminodisazo compound with a nitrobenzoyl chloride, reducing the nitro group, diazotizing, coupling with an amine free from hydroxy groups, and acylating the amino group by condensation with a carboxylic compound, e.g. with benzoyl chloride or p-nitrobenzoyl chloride. When p-nitrobenzoyl chloride is used in the final stage the nitro group may be reduced.  When the product contains a free amino group it may be diazotized upon the fibre and coupled with a component. The following examples are specified: (1) The dyestuff 2-naphthylamine-6 : 8-disulphonic acid --> m-toluidine is condensed with p-nitrobenzoyl chloride, the nitro group is reduced, the aminoazo product is diazotized and coupled with m-toluidine, and the aminodisazo compound is condensed with p  benzoyl chloride; the product dyes cotton bright yellow shades fast to washing and light, and cotton-silk fibre in uniform shades; the dyeings are dischargeable with hydrosulphite; if the benzoyl chloride in the last condensation is replaced by acetic anhydride the shades are slightly redder; if p-nitrobenzoyl chloride is used the nitro group may be reduced, the product yielding dyeings which may be diazotized on the fibre and developed with b -naphthol or 1-phenyl-3-methyl-5-pyrazolone to bright yellowish orange or bright yellow shades respectively, fast to washing and light.  (2) The dyestuff sulphanilic acid --> m-toluidine is condensed with p-nitrobenzoyl chloride, the nitro group is reduced, the aminoazo product is diazotized and coupled with 1-naphthylamine-6-sulphonic acid, the aminodisazo compound is condensed with p-nitrobenzoyl chloride, and the nitro group is reduced; the product dyes cotton yellowish orange shades which may be diazotized on the fibre and developed with b -naphthol or 1-phenyl-3-methyl-5-pyrazolone to orange-brown or bright yellowish brown shades respectively, fast to washing and light.  (3) The dyestuff 2-naphthylamine-6 : 8-disulphonic acid --> 1-naphthylamine - 6 - sulphonic acid is condensed with p-nitrobenzoyl chloride, the nitro group is reduced, the aminoazo product is diazotized and coupled with m-toluidine, and the aminodisazo compound is condensed with benzoyl chloride; the product dyes cotton slightly redder shades than the corresponding dyestuff of example (1) and on cotton-silk fibre gives a weaker dyeing on the silk than on the cotton; if the benzoyl chloride in the last condensation is replaced by p-nitrobenzoyl chloride and the nitro group is reduced, the dyeings may be diazotized on the fibre and developed with b -naphthol or 1-phenyl-3-methyl-5-pyrazolone to bright yellowish orange or bright yellow shades respectively.  Other components specified are, as first components, metanilic, anilinedisulphonic, toluidinesulphonic, naphthylaminesulphonic, 2-naphthylamine-4 : 8-disulphonic, and 2-naphthylamine-3 : 6-disulphonic acids, and as second or third components, aniline, p-xylidine o-anisidine, a -naphthylamine, and 1-naphthylamine-7-sulphonic acid.